Sparrows are like avian cockroaches. Don't forget fowl pox. We had a horrible run of pox the end of this summer. The mosquitoes were so bad, even hiding in the nest boxes during the heat of the day only to come out at night to attack the chickens. Of course the virus is carried by the wild birds, and the sparrows are everywhere. I ended up cutting fresh lemon grass and putting in the nest boxes, coop and run several times a week to help repel the mosquitoes. Still trying to plug every hole the sparrows can squeeze through.